The present invention relates to the derivatives of specially substituted azole compounds which have improved antifungal activity as compared with presently available agents in this class and the processes for the preparation thereof. This invention also relates to pharmaceutical preparations containing the compounds of the present invention and their use in treating and/or preventing the fungal infections in mammals, preferably humans.
Life threatening, systemic fungal infections continue to be a significant problem in health care today. In particular, patients who become xe2x80x9cimmunocompromisedxe2x80x9d as a result of diabetes, cancer, prolonged steroid therapy, organ transplantation anti-rejection therapy, the acquired immune deficiency syndrome (AIDS) or other physiologically or immunologically comprising syndromes, are especially susceptible to opportunistic fungal infections.
Since the 1950s and 1960s and until recently, the key opportunistic fungal pathogens with which clinicians had to contend were Candida albicans, Asperigillus fumigatus, and the zygomiycetes, which cause mucormycosis, a rapidly fatal infection especially in diabetic patients. Today, non-albicans Candida have become more frequent, as have other Aspergillus species. Candida species are now the fourth most common cause of nosocomial blood stream infection and they are associated with an extremely high mortality rate of 40%. From 1980 to 1990, the incidence of fungal infections in the US hospitals nearly doubled, from 2.0 to 3.8% of patients discharged. The most marked increase in fungal infection rates occurred not only in transplant units or oncology centers, but also in surgical services. These changing patterns demonstrate that fungal infections are no longer limited to the most severly immunosuppressed patients.
During the past two decades, a substantial shift in the epidemiology of candidemia due to different Candida species has occurred. In the 1960s and 1970s, Candida albicans accounted for 85-90% of cases of candidemia. In 1999, however, only 42% of candidemia cases were caused by C. alibicans, while non-albicans candida accounted for the remainder.
Cryptococosis is a leading cause of morbidity among AIDS patients. The incidence of life threatening cryptococcal infection among these patients have been estimated to vary from 10 to 30%. During initial therapy, 10-20% of these patients die and 30 to 60% patients succumb within a year. Penicillinium marneffei has been frequently isolated from HIV+ patients, especially in Southeast Asia.
The most common causative agent of mucormycosis is rhizopus, a common bread mould that lives on any organic material. Other pathogens include Mucor, Rhizomucor and Absidia. Zygomycetes include twenty different fungi, all appearing the same histologically. The severely immunocompromised patient may become infected with zygomycetes via respiratory inhalation.
Fusarium is the most prevalent plant fungus worldwide, and it is now recognized as human pathogen as well. Fusarium infections can occur in immunocompetent or immuno suppressed individuals. Fusarium infection is life-threatening and associated with a poor prognosis.
Penicillium marneffei is an environmental fungi that can cause serious, life-threatening infections in immunosuppressed patients. Penicillium marneffei has gained particular attention during the AIDS pandemic, as it may produce disease that is clinically indistinugishable from disseminated histoplasmosis.
Invasive aspergillosis has also become a leading cause of death, mainly among patients suffering from acute leukaemia or after allogenic bone marrow transfusion and after cytotoxic treatment of these conditions. It also occurs in patients with condition such as AIDS and chronic granulomatous disease. At present, only Amphotericin B and itraconazole are available for treatment of aspergillosis. Inspite of their activity in-vitro, the effect of these drugs in-vivo against Aspergillus fumigatus remains low and as a consequence mortality from invasive aspergillosis remains high.
Over the last three decades important progress has been made in the therapy of systematic fungal infections. Although chemotherapeutic agents such as flucytosine and potassium iodide are effective against selected fungal diseases, the primary drugs used to treat systemic mycoses are amphotericin B and the azole compounds. Despite the general effectiveness of amphotericin B, it is associated with a number of complications and unique toxicities that limit its use. Furthermore, the drug is poorly absorbed from the gastrointestinal tract necessitating intravenous administration. In addition, amphotericin B penetrates poorly into cerebrospinal fluid (CSF) of both normal and inflamed meninges.
The problems associated with amphotericin B have stimulated search for new agents. Within the available drugs to treat fungal infections, the azole class appears to be most promising. This class of compounds inhibits the biosynthesis of ergosterol in fungi, which is the main constituent of fungal cell membrane. Of the various representative antifungals, early azoles used were clotrimazole, miconazole, and tioconazole, which were potent against a wide range of fungi pathogenic to human. Clortrimazole was the first oral azole proven to be effective in experimental and human mycosis. However, brief courses of treatment with clotrimazole lead to the induction of liver microsomal enzymes which in turn increase the metabolism of the drug, thereby diminishing its antifungal activity. In contrast, miconazole, which became available around the same time as clotrimazole, is not rapidly metabolized and is an effective intravenous therapy for many systemic fungal diseases. Unfortunately, the use of miconazole is limited by its multiple toxic effects.
The in-vitro activity of clotrimazole, miconazole and tioconazole was not well exhibited in in-vivo models due to poor oral bioavailability and metabolic vulnerability. Ketoconazole was the first drug that could be used against systemic fungal infection and successfully delivered through oral route. However, it was still quite susceptible to metabolic inactivation and also caused impotence and gynacomastia probably due to its activity against human cytochrome P450 enzymes.
Even with the advent of ketoconazole, the search for improved antifungal azole agents has continued due in part to concerns over the potential for toxicity and poor penetration into cerebrospinal fluid (CSF) associated with ketoconazole. Several azoles have been developed as topical agents primarily directed at superficial candidal and dermatophytic infections.
Fluconazole is the current drug of choice for treatment of severe infections caused by Candida species and C.neoformans. However, fluconazole has only weak activity against isolates of Aspergillus species [minimum inhibitory concentration (MIC) values of 400 xcexcg/ml], since the drug has low potency (IC50=4.8 xcexcM) against lanosterol 14xcex1-de-methylase, the target enzyme in the fungus. Itraconazole, another triazole antifungal compound, generally is more active than fluconazole in the treatment of aspergillosis, but its activity in the clinic remains mixed as it showed variable oral availability, low solubility and very high protein binding besides causing ovarian cancer in animals.
The development of the earlier compounds which included SCH 39304 (Genoconazole), SCH 42427 (Saperaconazole) and BAY R 8783 (Electrazole) had to be discontinued as a result of safety concerns. Another promising triazole, D0870, a derivative of fluconazole, exhibited significant variations in plasma pharmacokinetics besides having weak anti-Aspergillus activity. Other fluconazole derivatives in different stages of development include Voriconazole and ER 30346 (BMS 207147). Voriconazole also shows non-linear pharmacokinetics besides some concern regarding its ocular toxicity. ER 30346""s anti-aspergillus activity, both in-vitro and in-vivo, is at best, only equal to itraconazole""s activity. SCH 56592 is a hydroxylated analogue of itraconazole with potent in-vitro and in-vivo activity, but is undetectable in CSF even when the serum drug concentration after several days of treatment are 25 to 100 times above the MIC for the most resistant C. neoformans. Thus, the potent activity of SCH 56592 for C. neoformans is partially negated by its low concentration at the site of infection in the central nervous system. The above candidates of azoles are discussed in the following publications:
SCH 56592; Antimicrobial agents and chemotherapy, 40, 1910 (1996); 36th Interscience Confernece on Antimicrobial agents and chemotherapy, September, 1996, New Orleans, Abst. To F-87-F-102.
TAK-187; 36th Interscience Conference Antimicrobial agents and Chemotherapy, September, 1996, New Orleans, Abst. F 74; EP 567892.
TAK-456 and TAK-457; 40th Interscience Conference on Antimicrobial agents and chemotherapy, Toronto, Canada, Abs. No. 1085 and 1086; U.S. Pat. No. 6,034,248.
ER-30346: Drugs of the Future, 21, 20 (1996).
Various derivatives of azole compounds have been covered in U.S. Pat. No. 5,371,101 assigned to Takeda. But none of them satisfies the medical needs completely, as they offer a limited spectrum of activity and low potency.
Thus, the antifungals available in the market suffer with drawbacks such as toxicity, narrow spectrum of activity and fungistatic profile rather fungicidal. Some of them also exhibit drug-drug interactions and, as a result, therapy becomes complex. In view of the high incidence of fungal infections in immunocompromised patients and the recent trends for the steady increase of the population of such patients, demands for new antifungal agents with broad spectrum of activity and good pharamcokinetic properties has increased. The continuing demand for safe and effective broad spectrum antifungal agent with favourable pharmacokinetic properties has spurred both the design and development of new systemically active antifungal triazoles.
Despite the therapeutic success of fluconazole and itraconazole, there remains a significant need for improved, broad spectrum, fungicidal rather than fungistatic, better tolerated, less toxic, safe at efficacious doses and more potent antifungal compounds with minimal potential for development of resistance among target fungi. Therefore, development of antifungal agents is still a big challenge.
The present invention relates to new substituted azole compounds which can be utilized to treat and/or prevent the fungal infections in mammals, preferably in humans.
The first aspect of the present invention provides compounds of Formula I, and its pharmaceutically acceptable salts, enantiomers, diastereomers, N-oxides, prodrugs or metabolities, 
wherein X is selected from the group consisting of CH2, CO, CS and SO2;
Ar is a substituted phenyl group having one to three substituents independently selected from a halogen (e.g., fluorine, chlorine, bromine, or iodine), C1-C4 alkyl, halogenated lower (C1-C4) alkyl group and halogenated lower (C1-C4) alkoxy group such as 2,4-difluorophenyl, 2,4-dichlorophenyl, 4-chloropheny), 4-fluorophenyl, 2-chlorophenyl, 2-fluorophenyl, 4-trifluoromethylphenyl, 2-fluoro-4-chlorophenyl, 2-chloro-4-fluorophenyl, 4-trifluoromethoxyphenyl, 2,4,6-trifluorophenyl, 4-bromophenyl;
R1 and R2 are each independently selected from the group consisting of hydrogen, C1-C4 alkyl, C1-C4 alkoxy, amino, hydroxy, nitro, cyano, carboxyl, protected carboxyl, and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl;
Y is a phenyl group which is unsubstituted or substituted by 1-3 substituents each independently selected from the group consisting of halogen, nitro, amino, cyano, carboxyl, protected carboxyl, hydroxy, C1-C4 alkyl, C1-C4 alkoxy and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl;
R3 is selected from the group consisting of hydrogen, C1-C4 alkyl group, C1-C4 alkoxy, nitro, amino, cyano, carboxyl, protected caboxyl and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl, and
X1, X2, Y1, Y2 and Z are independently selected from the group consisting of hydrogen halogen, nitro, cyano, amino, sulphonyl, aryl, C1-C4, alkyl, C1-C4 alkoxy, halogenated lower (C1-C4) alkyl group, halogenated lower (C1-C4) alkoxy group and carboxyl, or protected carboxyl.
When R1 is other than hydrogen, Formula I has two asymmetric centers and there are four possible enantiomers i.e. RR, RS, SR and SS. This invention relates to the mixture of enantiomers as well as individual isomers and the most preferred isomer in this situation is RR.
According to the second aspect of the invention, there are provided compounds of Formula II, and its pharmaceutically acceptable salts, enantiomers, diastereomers, N-oxides, prodrugs or metabolities, 
wherein X, Ar, R1, R2, X1, X2, Y1, Y2 and Z are the same as defined earlier.
When R1 is other than hydrogen, Formula II has two asymmetric centres and there are four possible enantiomers i.e. RR, RS, SR and SS. This invention relates to the mixture of enantiomers as well as individual isomers and the most preferred isomer in this situation is RR.
It has now been found that the compound namely, 2-{[1R,2R]-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl}-4-(2xe2x80x2,2xe2x80x2,3xe2x80x2,3xe2x80x2-tetrafluoropropoxyphenyl)-3-(2H,4H)-1,2,4-thiotriazolone has unexpectedly potent activity against clinically important filamentous species of fungi, besides increased spectrum. The compound is shown to be fungicidal against some filamentous fungi.
Pharmaceutically acceptable, non-toxic acid addition salts of the compounds of the present invention of Formulae I and II, may be formed with inorganic or organic acids, by methods well known in the art.
It is also an object of the invention to provide a method for synthesis of the novel compounds.
It is further object of the present invention to provide compositions containing the novel compounds of the present invention in the treatment of fungal infections.
The present invention also includes within its scope prodrugs of the compounds of Formulae I and II. In general, such prodrugs will be functional derivatives of these compounds which readily get converted in-vivo into defined compounds. Conventional procedures for the selection and preparation of suitable prodrugs are known.
The invention also includes pharmaceutically acceptable salts, enantiomers, diastereomers, N-oxides, prodrugs, metabolites in combination with pharmaceutically acceptable carriers and optional excipients.
Other advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the invention.
In order to achieve the above mentioned aspects and in accordance with the purpose of the invention as embodied and described herein, there are provided processes for the synthesis of compounds of Formulae I and II, wherein X, Ar, R1, R2, R3,Y, X1, X2, Y1, Y2 and Z are the same and defined earlier. The starting compounds of Formulae III and IV are known from our published PCT application WO 01/66551 and U.S. Pat. No. 5,371,101, respectively and are incorporated herein by reference. 
In Scheme I there is provided a process for preparing a compound of Formula I, as shown above and its pharmaceutically acceptable salts, enantiomers, diastereomers, N-oxides, prodrugs, or metabolites,
wherein X is selected from the group consisting of CH2, CO, CS and SO2;
Ar is a substituted phenyl group having one to three substituents independently selected from a halogen (e.g., fluorine, chlorine, bromine, or iodine) C1-C4 alkyl, halogenated lower (C1-C4) alkyl group and halogenated lower (C1-C4) alkoxy group such as 2,4-difluorophenyl, 2,4-dichlorophenyl, 4-chlorophenyl, 4-fluorophenyl, 2-chlorophenyl, 2-fluorophenyl, 4-trifluoromethylphenyl, 2-fluoro-4-chlorophenyl, 2-chloro-4-fluorophenyl, 4-trifluoromethoxyphenyl, 2,4,6-trifluorophenyl, 4-bromophenyl;
R1 and R2 are each independently selected from the group consisting of hydrogen, C1-C4 alkyl, C1-C4 alkoxy, amino, hydroxy, nitro, cyano, carboxyl, protected carboxyl, and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl;
Y is a phenyl group which is unsubstituted or substituted by 1-3 substituents each independently selected from the group consisting of halogen, nitro, amino, cyano, carboxyl, protected carboxyl, hydroxy, C1-C4 alkyl, C1-C4 alkoxy and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl;
R3 is selected from the group consisting of hydrogen, C1-C4 alkyl group, C1-C4 alkoxy, nitro, amino, cyano, carboxyl, protected caboxyl and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl, and
X1, X2, Y1, Y2 and Z are independently selected from the group consisting of hydrogen, halogen, nitro, cyano, amino, sulphonyl, aryl, C1-C4 alkyl, C1-C4 alkoxy, halogenated lower (C1-C4) alkyl group, halogenated lower (C1-C4) alkoxy group and carboxyl, or protected carboxyl.
When R1 is other than hydrogen, Formula I has two asymmetric centers and there are four possible enantiomers i.e. RR, RS, SR and SS. This invention relates to the mixture of enantiomers as well as individual isomers and the most preferred isomer in this situation is RR;
which comprises reacting the appropriate oxo compound of Formula III, wherein X, Ar, R1, R2, Y, R3, X1, X2, Y1, Y2 and Z have the same meanings as defined above, with modified Lawesson""s reagent of Formula V, to afford the desired compound of Formula I. The oxo compound of Formula III may be prepared according to the procedure as disclosed in our published PCT application WO 01/66551. The modified Lawesson""s reagent is prepared according to the procedure as disclosed by Masataka Yokohamna et al. in Synthesis, pp 827-829 (1984). 
In Scheme II there is provided a process for preparing a compound of Formula II, as shown above and its pharmaceutically acceptable salts, enantiomers, diastereomers N-oxides, prodrugs or metabolities,
wherein X is selected from the group consisting of CH2, CO, CS and SO2;
Ar is a substituted phenyl group having one to three substituents independently selected from a halogen (e.g., fluorine, chlorine, bromine, or iodine), C1-C4 alkyl, halogenated lower (C1-C4) alkyl group and halogenated lower (C1-C4) alkoxy group such as 2,4-difluorophenyl, 2,4-dichlorophenyl, 4-chlorophenyl, 4-fluorophenyl, 2-chlorophenyl, 2-fluorophenyl, 4-trifluoromethylphenyl, 2-fluoro-4-chlorophenyl, 2-chloro-4-fluorophenyl, 4-trifluoromethoxyphenyl, 2,4,6-trifluorophenyl, 4-bromophenyl;
R1 and R2 are each independently selected from the group consisting of hydrogen, C1-C4 alkyl, C1-C4 alkoxy, amino, hydroxy, nitro, cyano, carboxyl, protected carboxyl, and SO2Rxe2x80x2 wherein Rxe2x80x2 is hydrogen, alkyl or aryl; and
X1, X2, Y1, Y2 and Z are independently selected from the group consisting of hydrogen, halogen, nitro, cyano, amino, sulphonyl, aryl, C1-C4, alkyl, C1-C4 alkoxy, halogenated lower (C1-C4) alkyl group, halogenated lower (C1-C4) alkoxy group and carboxyl, or protected carboxyl.
When R1 is other than hydrogen, Formula II has two asynmetric centers and ther are four possible enantiomers i.e. RR, RS, SR and SS. This invention relates to the mixture of enantiomers as well as individual isomers and the most preferred isomer in this situation is RR; which comprises reacting the oxo compound of Formula IV, wherein X, Ar, R1, R2, X1, X2, Y1, Y2 and Z have the same meanings as defined above, with modified Lawesson""s reagents [prepared according to the procedure as disclosed by Masataka Yokohama et al in Synthesis, pp 827-829 (1984)] of Formula V, to afford the desired compound of Formula II. The starting compound of Formula IV is prepared by following the procedure as disclosed in the U.S. Pat. No. 5,371,101.
In the above schemes where specific solvent and specific modified Lawesson""s reagent are mentioned, it is to be understood that other solvents and Lawesson""s reagent or modification thereof may be used. Similarly, the reaction temperature and duration of the reaction may be adjusted according to the need. An illustrative list of some of the compounds according to the invention and capable of being produced by Schemes I and II include:
Compound No. 1: 2-{[1R2R]-2-(2,4-Difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazole-1-yl)propyl}-4-{4-[4-(4-chlorophenyl)-1-piperizinyl]phenyl}-3-(2H,4H)-1,2,4-thiotriazolone
Compound No. 2: 2-{[1R2R]-2-(2,4-Difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazole-1-yl)propyl}-1-[4-(4-methoxyphenyl)-3-(2H,4H)-1,2,4-thiotriazolone
Compound No. 3: 2-{[1R,2R]-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl}-4-(2xe2x80x2,2xe2x80x2,3xe2x80x2,3xe2x80x2-tetrafluoropropoxyphenyl(-3-(2H,4H)-1,2,4-thiotriazolone
The examples mentioned below demonstrate the general synthetic procedure as well as specific preparation for the preferred compound. The examples are given to illustrate the details of the invention and should not be constrained to limit the scope of the present invention.
The compounds were characterized using NMR, IR and were purified by chromatography. Crude products were subjected to column chromatographic purification using silica gel (100-200 or 60-120 mesh) as stationary phase.